5ji2
HslU L199Q in HslUV complexHslU L199Q in HslUV complex
Structural highlights
Function[HSLV_ECO55] Protease subunit of a proteasome-like degradation complex believed to be a general protein degrading machinery. [HSLU_ECO57] ATPase subunit of a proteasome-like degradation complex; this subunit has chaperone activity. The binding of ATP and its subsequent hydrolysis by HslU are essential for unfolding of protein substrates subsequently hydrolyzed by HslV. HslU recognizes the N-terminal part of its protein substrates and unfolds these before they are guided to HslV for hydrolysis. Publication Abstract from PubMedThe I domain of HslU sits above the AAA+ ring and forms a funnel-like entry to the axial pore, where protein substrates are engaged, unfolded, and translocated into HslV for degradation. The L199Q I-domain substitution, which was originally reported as a loss-of-function mutation, resides in a segment that appears to adopt multiple conformations as electron density is not observed in HslU and HslUV crystal structures. The L199Q sequence change does not alter the structure of the AAA+ ring or its interactions with HslV but increases I-domain susceptibility to limited endoproteolysis. Notably, the L199Q mutation increases the rate of ATP hydrolysis substantially, results in slower degradation of some proteins but faster degradation of other substrates, and markedly changes the preference of HslUV for initiating degradation at the N or C terminus of model substrates. Thus, a structurally dynamic region of the I domain plays a key role in controlling protein degradation by HslUV. A Structurally Dynamic Region of the HslU Intermediate Domain Controls Protein Degradation and ATP Hydrolysis.,Baytshtok V, Fei X, Grant RA, Baker TA, Sauer RT Structure. 2016 Oct 4;24(10):1766-1777. doi: 10.1016/j.str.2016.08.012. Epub 2016, Sep 22. PMID:27667691[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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